tuple.index()

[Fredrik Lundh]

Nick Maclaren wrote:

> My understanding of the difference between a tuple and a list is
> PRECISELY that the former is immutable and the latter mutable.

while tuples can be used as "frozen lists", that's definitely not what 
they are, from a design perspective.

just like in math [1], a Python tuple is a heterogeneous sequence where 
the position implies type and usage.  in contrast, a list is a homo- 
geneous collection where all the items are "the same" in some sense,
no matter where they are.  if you sort or otherwise reorder a list
of things, it's still a list of the same things.  if you sort a tuple, 
you'll break it.

in other words, you're supposed to know what the individual items are in 
a tuple; if you feel the need to search for things by value in a tuple, 
you're using the wrong container type.

</F>

1) http://en.wikipedia.org/wiki/Tuple